1. Field of the Invention
The present invention relates to discriminators for use in phase lock loops and frequency lock loops of a communication receiver. More particularly the present invention relates to a novel programmable digital frequency discriminator which is command programmable to operate as a phase discriminator.
2. Description of the Prior Art
Heretofore, analog phase lock loops have been provided with frequency sweep circuits. Such adjunct circuits were employed to achieve frequency acquisition lock and then disabled so that the phase could be acquired and tracked by the phase lock loop.
Heretofore, digital frequency lock loops and digital phase lock loops have been proposed as separate circuits on separate semiconductor chips. Such circuits have been arranged in a module or as additional circuitry to be sequentially operated, however, this would create a condition or requirement for additional logic circuit chips and/or discrete components. There is a present need for a simple and inexpensive digital discriminator capable of being implement on a single very large scale integrated circuit that is externally programmable.